The U.S. policy shift only adds to the uncertainty hanging over Cuba, as Cuban President Raúl Castro has promised to step down in 2018.

But the core of Obama's Cuba rapprochement remains in tact. Here are how ties with Cuba have changed — and haven't changed — under the Trump administration.

Diplomatic relations

The frosty relationship between the U.S. and Cuba thawed significantly under Obama, but Trump is threatening to cool things back down.

The president, who kept diplomatic ties with Cuba, said this summer that the U.S. will not lift sanctions on the island unless the government meets a series of benchmarks, including the release of political prisoners, free elections and the legalization of political parties.

Trump has also slammed Raúl Castro for human rights abuses and announced new rules — finalized in early November — aimed at restricting the flow of U.S. dollars to the oppressive regime.

The harder line on Cuba also comes at a time of heightened tensions between Washington and Havana over what the U.S. government has described as “sonic attacks” against its diplomats in Cuba.

The Cuban government has said it did not carry out any attacks against American representatives, but the Trump administration has said that Havana is ultimately responsible for ensuring diplomats’ safety.

The unexplained incidents have prompted the U.S. to withdraw the majority of its embassy staff from Havana and eject most Cuban diplomats from their embassy in Washington.

But Trump has still kept the U.S. Embassy’s lights on, and has kept Cuba off a list of state sponsors of terror. Trump also did not bring back the “wet foot, dry foot” immigration policy that allowed Cuban migrants who made it to the U.S. to stay in the country.

“Our embassy remains open in the hopes that our countries can forge a much better path," Trump said this summer when he announced his new policy.

Business ties

Under Trump’s new Cuba policy, financial transactions that benefit the Cuban military business arm, known as the Grupo de Administración Empresarial (GAESA), are prohibited.

The military-controlled conglomerate is involved in nearly all sectors of the Cuban economy, but tourism is its crown jewel.

The U.S. Commerce and Treasury departments identified 180 entities and sub-entities that will now be off-limits to Americans under the new regulations. The list includes hotels, stores, tourist agencies, rum companies, beverage manufacturers and marinas.

But the new restrictions do not apply to deals that have already been inked. That's why Four Points by Sheraton Havana, which is operated by GAESA and became the first U.S. hotel to come to Cuba in more than 50 years, is not on the list of prohibited entities.

The exemption for current deals underscores the White House's struggle to balance its promised crackdown on Cuba with the interests of U.S. businesses, which overwhelmingly supported Obama’s rapprochement with the island nation.

Travel

Tourism to Cuba has long been prohibited, but Obama relaxed U.S. travel rules by allowing Americans to visit the island under 12 different travel categories under a general license.

The Trump administration took aim at one of the most popular categories, which the White House said travelers have been abusing.

The U.S. government is no longer allowing individual “people-to-people” trips. The subcategory has enabled American travelers who want to visit Cuba for educational purposes to design their own trips and visit the island on their own.

Now, Americans can only travel under that category if they go through a licensed tour group.

But travelers can still visit Cuba under every other category of travel, including the category of "Support for the Cuban People.”

Commercial air service between the U.S. and Cuba, which resumed for the first time in over 50 years last summer, will also still be allowed to continue under Trump. Some lawmakers had tried to halt commercial flights to the island last year.

But travelers could see stepped up enforcement when they return home to the U.S. They are required to maintain full schedules and keep detailed logs while in Cuba — something that is rarely checked. But senior officials warned that the administration would be conducting more audits now.

Trade

Only Congress can lift the trade embargo on Cuba, but Obama eased trade restrictions by allowing the import of charcoal, coffee and certain textiles from the island. He also allowed U.S. companies to export telecommunications equipment and other goods that support the Cuban people.

Those policies have been largely untouched by the Trump administration.

A popular rule allowing Americans to bring back an unlimited amount of rum and cigars also remains intact.

But while Trump’s new regulations don’t specifically reverse any of Obama’s trade policies, U.S. companies are now restricted from doing business with any entities linked to the Cuban military, which could impact trade efforts between the two countries.

Individual Cuban sanctions

Trump’s policy expands the definition of “prohibited officials” in Cuba.

Americans are banned from engaging in direct financial transactions with any Cuban nationals on the prohibited list, which includes people who work for certain Cuban government ministries.

Under Trump, less people will now be eligible to receive remittances from their Cuban-American families in the U.S.

However, Trump kept an Obama-era policy that removed the cap on the amount of remittances that U.S. citizens can send to their Cuban relatives.